It is known in the art to separate particles of gold and other heavy metals from lighter weight dust and dirt by use of a current of water. Apparatus to perform this function with water range from relatively small, e.g. a swirling basin of water containing gold-bearing soil, to very large, e.g. focusing a high-speed water jet on gold-bearing soil and allowing the water-soil mixture to trickle over one or more riffle boards. The first method is extremely slow and time consuming, and the second requires an available large supply of water, and also generates a large amount of debris, so much so that large-scale hydraulic mining is illegal in all states.
To circumvent the problems of hydraulic mining, some have reported the use of air separation of metals. For instance, Snee in U.S. Pat. No. 839,329, discloses the details of an air separation of metals from ores. This device includes a hopper arrangement whereby the raw ore is fed into a hopper and directly impinges on a screen separator. Beneath the screen arrangement is a supplemental chute leading to and discharging into a box which forms a part of a separating chute. The upper portion of the chute serves to remove the coarser portions of the material thrown into the hopper and to deliver the smaller screened and more valuable ore particles to the chute there beneath. The lower chute is in communication with the discharge end of a fan by means of a duct or air passage. The sieved or sifted ore enters the chute and is met by an air blast from an air chamber which carries the lighter portions of the screened ore particles over the opening forming the chute. The openings have inwardly and rearwardly inclined sides. The metals and other heavy metal-containing particles drop to the floor of the chute. The chute may also be caused to vibrate in a side-to-side manner so as to cause the material to slowly travel downward and be constantly agitated so as to give the air blast more of an opportunity to remove the lighter dust particles from the ore. The device of Snee involves a single large flow air blast to separate the metals from the dust and dirt. In addition, Snee does not disclose a light-weight portable ore-separating apparatus or one in which certain elements of the apparatus are detachable to enhance the portable nature of the apparatus.
Other disclosures of general interest include those which describe the cleaning of dust and debris from grain. For instance, Hatfield, in U.S. Pat. No. 1,985,167, discloses the use of a grain cleaning apparatus that incorporates a crank-operated fan to provide an air flow for separating dust, debris and chaff from grain. The air flow passes over the grain that has settled in the depression of an inclined slideable arm to the crank, so that agitation of the board results from the operation of the crank. Also, in U.S. Pat. No. 1,321,263, Vaughn describes a grain separator having a series of screens, a feed roll hopper assembly having a fan, and a chute to provide an air blast to further separate the dust from the grain. Further, in U.S. Pat. No. 2,071,267, Schneider discloses an apparatus for the cleaning and separation of grain, and also for the separation of grain by size. The grain is passed through a series of progressively smaller sieves. A blast of air entering in a perpendicular direction to the screens is used to remove chaff and other foreign substances from the grain.
While the above references describing the separation of grain from lighter materials, such as chaff, may be of general interest, none suggest their adaption to treat a material as different as metal and rock nor do they teach a portable lightweight apparatus as described in the present invention.
It is therefore an object of the present invention to provide a portable lightweight apparatus for the air separation of metals, such as gold, from lighter weight materials.
It is a further object of the present invention to provide a portable lightweight apparatus which is compact and has certain elements, such as the separator and hopper, which are easily detachable to improve portability.
Another object of the present invention is providing an apparatus of the above-cited character which is simple and durable in construction, reliable and efficient in operation and inexpensive to manufacture.
Other objects and advantages of the invention will be apparent during the course of the following description.